iPhone: Be careful when editing the APN
Certain carriers allow you to edit the Access Point Name (APN) on iPhone. This may cause unexpected results, for example if you edit the APN that was previously set for you by your IT Manager via a configuration profile.
If you are using iPhone in an enterprise environment, your IT manager may have set up a special APN for you to use. If this is the case, do not edit the APN directly on iPhone. Contact your IT Manager if you want to change your APN.
If you accidentally changed your APN after your IT Manager set it for you via a configuration profile, you can set it back by removing the configuration profile and then adding it back. For more information, contact your IT Manager.
Note that an incorrect APN may disable all data services until it is set back to to the correct APN. If you are not using a configuration profile, contact the carrier of the SIM card you are using. For further information click here.